Abstract

The ring–liner interface of an internal combustion engine is a very important interface because its behavior directly affects fuel efficiency of an automobile and the engine life. The liner surface is complicated, with honing features on top of the primary roughness. Moreover, liner surfaces considered here also contain pores that are random in terms of their shape and distribution. The work reported in this article systematically models the tribological performance of such surfaces in a ring–liner interface. A microscopic single-pore computational fluid dynamics analysis is conducted on the representative pore shape obtained from liner–surface characterization to quantify the effect of pores on friction. A pore influence zone is suggested, and a friction reduction factor is defined for pores. A macroscopic ring–liner interface model is developed in parallel to solve the average Reynolds equation for a representative section with the consideration of the starvation and cavitation effects. The two models are then combined to predict friction at the ring–liner interface for the liner surfaces with pores. Excellent agreement is observed between our modeling and experimental results. The effects of random pores of varying densities in the range of 2–10% on the ring–liner interface performance are studied under flooded and starved conditions. The results indicate that surface pores increase friction when the ring–liner set is operated under flooded conditions. However, when starvation occurs, surface pores help reduce friction.

摘要

内燃机的环衬界面是一个非常重要的界面，因为它的行为直接影响汽车的燃油效率和发动机寿命。衬板表面很复杂，在主要粗糙度的顶部具有珩磨特征。此外，这里考虑的衬里表面还包含形状和分布随机的孔。本文报道的工作系统地模拟了环形衬板界面中此类表面的摩擦学性能。对从衬管表面表征获得的代表性孔隙形状进行微观单孔计算流体动力学分析，以量化孔隙对摩擦的影响。建议使用孔隙影响区，并为孔隙定义摩阻系数。一个宏观的环形-线性界面模型被并行开发，以在考虑饥饿和空化效应的情况下求解代表性截面的平均雷诺方程。然后将这两个模型结合起来，预测带孔的衬管表面的环-衬管界面处的摩擦。在我们的建模和实验结果之间观察到了极好的一致性。研究了在淹没和饥饿条件下，密度在 2-10% 范围内变化的随机孔对环衬界面性能的影响。结果表明，当环衬套组在满水条件下运行时，表面孔隙会增加摩擦。然而，当饥饿发生时，表面孔隙有助于减少摩擦。